1. Field of the Invention:
This invention relates to a bottle labelling machine and, more specifically, to a support plate for a bottle turntable in such a labelling machine which includes means for insuring that bottles secured thereon will not be subjected to undesired rotation during the labelling process.
2. Description of the Prior Art:
To label bottles in labelling machines, it is customary to support the bottles axially between the bottom and top of the bottle so that they will not rotate. The bottle should be supported within the machine against undesired rotation so that the label can be transferred to the bottle during controlled rotating movement by the machine and, after the label is applied, can be pressed completely against the surface of the bottle by applicator mechanisms, such as brushes. The precision with which this is conducted depends, among other things, on how securely the bottles can be prevented from undesired rotation. Since the controlled rotary movement is produced through frictional contact between the bottle and the bottle turntable upon which the bottle is axially supported, it is not unusual to take special precautions to keep the bottle from slipping on the turntable. The danger of slipping is particularly great, because lubricants and water are used to wet the bottle on the conveyor mechanisms, e.g. plate conveyors, upstream of the labelling machine.
To prevent the bottles from slipping on the bottle turntable, the prior art includes the use of solutions which are intended to clean the bottom of the bottle before the bottle is placed on the bottle turntable. The prior art also includes the use of solutions which are intended to clean the bottle turntable as well.
These measures can be employed as an alternative to, or in addition to, the conventional precautions taken involving the turntable itself.
For example, one prior art device utilizes a support plate for bottle turntables in which radial grooves are introduced into the surface of an elastic body of the support plate which consists of solid rubber. Since the elastic body of such a support plate does not conform to the bottom of the bottle, it is impossible to achieve a 100% frictional engagement therebetween even if the bottle is secured to the support plate by a large axial force. This is particularly true if the bottom of the bottle and/or the contact surface of the support plate is wet or has a coating of lubrication as discussed in German Utility Model DE-GM 660 77 56.
Significantly better results have been achieved with a bottle turntable in which the elastic body of a support plate mounted thereon includes an elastic coating in which sharp-edged bodies or grains are imbedded. Because of the elastic material, this support plate is capable of conforming to the shape of the bottom of the bottle. On the other hand, the sharp-edged bodies which project out of the surface under axial pressure are hooked or engaged in the microfractures on the surface of the bottom of the bottle. The increased frictional engagement achieved in this manner, when compared to other support plates of the prior art, tends to meet the basic requirements for a non-slipping coupling between the support plate and the bottle. This non-slipping condition can only be achieved, however, if the bottle is axially braced with a relatively high axial force between bottom and top. Another disadvantage of such a support plate is that it is relatively expensive to manufacture. As a practical matter, such support plates do not last long in service, because during operation, the small, hard, sharp-edged bodies or grains are easily torn from the support plate as discussed in German Patent DE 35 14 239 C1. In practice, however, it has been found that a uniform elasticity of the elastic body is only possible when the sharp-edged bodies are imbedded in the upper region. Therefore, it is not uncommon to initially form a rod of elastic material with imbedded, sharp-edged bodies evenly distributed throughout. Such a rod is then cut into discs which serve as the elastic bodies for use in the support plates on bottle turntables. Since, as a rule, these discs which serve as elastic bodies are attached with adhesive to a pot-shaped support to form the support plate, it is difficult to achieve a permanent adhesive bond between the elastic bodies and the support.